No. It is an option to look into.
Advancement of fuel delivery?
- Thread starter Alky V6
- Start date
New direction. Next mission is to develop my own VSC system. With the present stall I'm getting on the nitrous (3500+), I might be able to get 4500 rpm stall using a VSC system. Should be simple enough. I'll use the transbrake buttom to activate the system and then one of the unused delay timers in my delay box to deactivate it.
It will be interesting developing it. This is the kind of stuff I enjoy about this project.
It will be interesting developing it. This is the kind of stuff I enjoy about this project.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
It's the only option I see for you if you plan to stick with the same turbo.
I have a new design converter than Freeman used on his 202mph pass that will spool your turbo but the issue is your rpm range. I think you said you shift at 7500 so it would not recover enough to really couple up.
The regular 9.5 like what Tony Gomes and Fiscus use to spool the 91mm they have been testing will have launch boost in 2 seconds without variable stall. Slip comes in around 8-9% on their 172 and 174mph passes. This may be something you'd want to try just to see if it's different. If your interested I'll see what I have and will send you one to test.
I have to agree with you on my available options, and I do appreciate the offer Dusty. I'm pretty sure I'm still going to need or at the least benefit from a VSC system, so let me get that squared away first and see how it does. I've already modded a pump and I'm drawing out the hydraulic schematic for the aux valve body. I'm going to add some other interesting features into the prototype also. I figure tuning in the T/C stall will be the last on the list after all other tuning parameters have been dialed in, or are at least very close. I'm kind of excited to see how a VSC system might help out in this situation.
I'm pretty sure I won't be giving up on this turbo anytime soon. When this monster does spool, it is amazing. I just need to figure out the systems to get it spooling quicker. There are a bunch of options still open to help me do that. More well known than others. Don't know if I might have to use all of them, but I'm going to give it a try.
I started doing some calcs with the nitrous system. I was interested in finding out what my maximum hp shot might be for this compression ratio and new turbo combination. With the T76, it was pretty clear from the calcs that around a 200 shot was going to be the ticket. And it clearly was. It worked out perfectly. It just dawned on me that I really hadn't revisited the nitrous system upper limit calculations since installing the new turbo. I was stuck on the assumption that around a 200hp shot would still be the limit with the new turbo. After some calcs, it looks like a 400hp 
shot will be the limit, as far as my personal limit on cylinder pressures are concerned. Surprisingly, a 325hp shot looks like a very happy target. The cylinder pressures are plenty safe, nitrous plus boost up to 16 psi, and the spool up is not too early in the rpm band. The possibility of 13 psi boost by 4,500 rpm. If it turned out to be just 8 psi by 4,500, that would be just fine.
I will be slowly working up on the nitrous shot level, mixture targets and tuneup while I develop the VSC system. A higher nitrous shot level along with a VSC system could be very exciting.
Some new possibilities just opened up.
shot will be the limit, as far as my personal limit on cylinder pressures are concerned. Surprisingly, a 325hp shot looks like a very happy target. The cylinder pressures are plenty safe, nitrous plus boost up to 16 psi, and the spool up is not too early in the rpm band. The possibility of 13 psi boost by 4,500 rpm. If it turned out to be just 8 psi by 4,500, that would be just fine.I will be slowly working up on the nitrous shot level, mixture targets and tuneup while I develop the VSC system. A higher nitrous shot level along with a VSC system could be very exciting.
Some new possibilities just opened up.
I appreciate your concern. A 400hp shot is unthinkable. Much like a 200 shot was unthinkable when I first let on that I would be trying that. I'm now at about a 245hp jetting and it feels like old hat. The math is supporting the effort so I'm going to give it a shot, so to speak. The plan is not to actually get to a 400 shot. Small steps. It'll be fine as long as I get the mixture and timing right, which will be starting out much more conservative than I've ever been in the past. I'll be watching the signs at each step.
How do I know that a vsc system is not going to starve a converter and burn it up. I've worked with automatic transmissions since the early 80s. It's basically been my career. I understand how they work pretty well. And yes, I also know enough about torque converters to get into trouble. The theory of vsc intrigues me. I understand the principle of operation and it will most certainly help my situation. I don't know what the exact effects of using the system will be for sure, but how I envision it working, I'm pretty sure it's not going to hurt anything.
Before I dial in the basic converter stall, I need to get these other parameters settled on. If Dusty's offer is still open at that point, I'd be more than happy to try one of his configurations.
I've never been known for doing things the easy way. Besides, I learn so much more this way.
Target a/f ratio at T/C stall
Tuning notes.
I was playing with the mixture at converter stall and found a 10.95:1 to 11.1:1 reading on my a/f ratio gauge gives me the highest stall speed in the quickest amount of time. Just 3 percent richer and the stall falls way off.
Stall at 10.95 to 11.1, 2757 rpm.
Stall at 10.65-10.7 (3 percent richer), 2440 rpm.
Going leaner causes an increase in time that it takes to achieve the target stall.
The difference in time is .4 seconds compared to going rich or lean only 1 percent from the optimum mixture target. I had to look that over 4 times to make sure I was reading the numbers right. O2 correction would not work well in this instance.
11.35:1 = .775 lambda = 5.00:1. Typical power mixture target with methanol.
10.95:1 = .748 lambda = 4.82:1. Best target for my combination.
10.65:1 = .727 = 4.69:1. Power falls very noticably.
10.7:1 = .730 = 4.71:1. Current max lean target for top end at 31 psi boost.
Higher boost a/f target to be determined.
Starting, coolant, iat, and accel enrichments working very well with the latest file 'Alky3.2 16r no nos'.
Tuning notes.
I was playing with the mixture at converter stall and found a 10.95:1 to 11.1:1 reading on my a/f ratio gauge gives me the highest stall speed in the quickest amount of time. Just 3 percent richer and the stall falls way off.
Stall at 10.95 to 11.1, 2757 rpm.
Stall at 10.65-10.7 (3 percent richer), 2440 rpm.
Going leaner causes an increase in time that it takes to achieve the target stall.
The difference in time is .4 seconds compared to going rich or lean only 1 percent from the optimum mixture target. I had to look that over 4 times to make sure I was reading the numbers right. O2 correction would not work well in this instance.
11.35:1 = .775 lambda = 5.00:1. Typical power mixture target with methanol.
10.95:1 = .748 lambda = 4.82:1. Best target for my combination.
10.65:1 = .727 = 4.69:1. Power falls very noticably.
10.7:1 = .730 = 4.71:1. Current max lean target for top end at 31 psi boost.
Higher boost a/f target to be determined.
Starting, coolant, iat, and accel enrichments working very well with the latest file 'Alky3.2 16r no nos'.
Ok, I see your ratios, which is A/F? I'm guessing the smaller ratios are based on o2's? Just trying to make sure I'm looking at this correctly.
Do you run 1 wideband or 1 per bank?
-Will
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
You've got so many variables to tune. I agree, you've got a lot to play with before you throw something else in the mix. At whatever point you decide you need more stall I'll do what I can.
You will most likely need some track time to see how the car behaves with the large turbo at the gear changes. At that point you'll have a better idea of what may be needed. Hopefully you can get the VSC system working to get you to that point.
I'm using 1 wideband at the Y junction just before the turbo.
My wideband is setup to readout gasoline ratios. That's the high numbers. The .7xx numbers are the lambda values based on the gasoline ratios. The lower ratio numbers are air/alky ratios based on the lambda numbers.
10.7(a/f readout from a wideband O2 meter calibrated for gasoline) / 14.64(stoich ratio of gasoline) = .731(lambda)
.731(lambda) X 6.45(stoich ratio for methanol) = 4.71(actual air/alky fuel ratio based on lambda number)
In general, I use the lambda value to convert the air/gasoline ratio to an air/methanol ratio. I'm doing the same thing the O2 meter does in taking a lambda value and converting it into an air/fuel(gasoline) ratio number that we can relate to more easily.
I think you're starting to grasp the picture.
This weekend I'll be tuning in the 245 shot, starting very rich and leaning it in until the plugs tell me stop or I reach a calculated n/f ratio of 2.0:1. At this point I'm not very interested in going leaner than 2.0:1 with the nitrous system. The past 200 shot I used with the T76 was run at a ratio range of 1.75 to 1.9 depending on bottle pressure. It definitely woke up whenever the bottle was hot. The timing retard will start at 18 degrees (3 degrees retard per 50 shot) and will move higher as the shot size does too. When I find the n/f ratio that the engine tolerates and operates well at, I'll have a good idea on how to treat the n/f ratios as I move up the ladder. When I've found a limit, or 325hp shot, whichever comes first, then I'll concentrate on the data that we'll need for determining a proper converter change.
Dusty. What numbers are you interested in at the shift changes? I can start getting some of that data together as I move on these other tuning changes so you can start getting an idea on how the numbers are moving, or not moving due to the changes.
I've been in the habit of using this thread to share tuning notes on my project. Seeing that some important ones were lost during the last blackout, or whatever you want to call it, all further notes will be kept internal. I may post them in a blog on my website sometime in the future.
I hope the past effort did turn on some light bulbs for some people.
End of thread.
I hope the past effort did turn on some light bulbs for some people.
End of thread.
Here it is.
DRW Transmission and Auto Care
New video of the project: YouTube - Sights and Sounds of Alky Buick V6 v3.2
DRW Transmission and Auto Care
New video of the project: YouTube - Sights and Sounds of Alky Buick V6 v3.2
You're right about that. My mistake. I have a plugged off O2 boss at the Y that I used a narrow band with before I went to a wide band. The wide band is about 12 to 16" after the turbo. My egt is also located at the Y. Sorry for the brain *art.
No, I haven't. The latest testing has given me clues that I may not need to raise the stall. The 245 shot worked pretty good. Got a 1.66 60 foot with boost ramping from 0 to less than 8 psi by the 60 foot mark. I still have some tuning in to do with the 245 shot, but maybe all I need is just a little more nitrous to get my target 60 foot of around 1.3. I already have the jetting for the next two step ups with the nitrous figured out. I want to completely tune in each step though before moving to the next level. The turbo is actually spooling pretty decent at this point too. 8 psi by 5850 rpm. Very reasonable. In fact, almost perfect. 300 rpm sooner would be the ticket. The higher shots should kick that up a little more too. 8 psi is looking like a good target boost to shut down the nitrous. The rpm and map rise is almost perfectly smooth. The new boost controller is going on before anymore testing. At this point, too much boost is building by the 1-2 shift and the tires go away, even with pedaling. The plan is coming together nicely.
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